The Gliders in IMC debate has been going on for many years. I started flying power in 1991 and remember the debate back then. Those that choose to fly in IMC are qualified and know the risks (both power and non power). In many respects the glider pilots honour the threat better than GA. A Glider pilot has a good chance of surviving a mid air, most GA pilots do not.
I regularly see Notams about gliding events. Perhaps it is worth adding to the Notam that large numbers of gliders may be IMC in the areas mentioned. Mr squeasyjet would then have to take the threat more seriously and might decide to use CAS.
Rod1